Tribological behavior of micro structured surfaces for micro forming tools

Brinksmeier, E.; Riemer, O.; Twardy, Sven

doi:10.1016/j.ijmachtools.2009.11.006

Cited by 74 publications

(32 citation statements)

References 9 publications

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“…In conventional forming processes, tribological conditions influence the material flow during forming and therefore affect the forming result significantly [28]. Figure 13 shows the effect of increasing friction factors on the die filling.…”

Section: Tribological Approachmentioning

confidence: 99%

Extension of the forming limits of extrusion processes in sheet-bulk metal forming for production of minute functional elements

Pilz¹,

Henneberg²,

Merklein³

2020

Manufacturing Rev.

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Increasing demands in modern production pose new challenges to established forming processes. One approach to meet these challenges is the combined use of established process classes such as sheet and bulk forming. This innovative process class, also called sheet-bulk metal forming (SBMF), facilitates the forming of minute functional elements such as lock toothing and gear toothing on sheet-metal bodies. High tool loads and a complex material flow that is hard to control are characteristic of SBMF. Due to these challenging process conditions, the forming of functional elements is often insufficient and necessitates rework. This negatively affects economic efficiency. In order to make use of SBMF in industrial contexts, it is necessary to develop measures for improving the forming of functional elements and thereby push existing forming boundaries. This paper describes the design and numerical replication of both a forward and a lateral extrusion process so as to create involute gearing in combination with carrier teeth. In a combined numerical-experimental approach, measures for extending the die filling in sheet-metal extrusion processes are identified and investigated. Here, the focus is on approaches such as process parameters, component design and locally adjusted tribological conditions; so-called 'tailored surfaces'. Based on the findings, fundamental mechanisms of action are identified, and measures are assessed with regard to their potential for application. The examined approaches show their potential for improving the forming of functional elements and, consequently, the improvement of geometrical accuracies in functional areas of the workpieces. This is an Open Access article distributed under the terms of the Creative Commons Attribution License (https://creativecommons.org/licenses/by/4.0), which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

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Section: Tribological Approachmentioning

confidence: 99%

Extension of the forming limits of extrusion processes in sheet-bulk metal forming for production of minute functional elements

Pilz¹,

Henneberg²,

Merklein³

2020

Manufacturing Rev.

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“…Surface texturing of the die was proposed by Brinksmeier et al [69] as another mean to control friction in sheet microforming applications and therefore prolong die life. Using a strip drawing test experiment, Brinksmeier et al [69] have shown that there is an optimum finish for which friction is the lowest and that a smoother surface finish does not necessarily correlate with less friction. Similar applications in the case of bulk forming have been reported by Geiger et al [70] and Wagner et al [28] where it was shown that proper surface texturing could increase die life.…”

Section: Critical Issues Particular To Microformingmentioning

confidence: 99%

Tool Wear and Life Span Variations in Cold Forming Operations and Their Implications in Microforming

et al. 2016

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Abstract:The current paper aims to review tooling life span, failure modes and models in cold microforming processes. As there is nearly no information available on tool-life for microforming the starting point was conventional cold forming. In cold forming common failures are (1) over stressing of the tool; (2) abrasive wear; (3) galling or adhesive wear, and (4) fatigue failure. The large variation in tool life observed in production and how to predict this was reviewed as this is important to the viability of microforming based on that the tooling cost takes a higher portion of the part cost. Anisotropic properties of the tool materials affect tool life span and depend on both the as-received and in-service conditions. It was concluded that preconditioning of the tool surface, and coating are important to control wear and fatigue. Properly managed, the detrimental effects from surface particles can be reduced. Under high stress low-cycle fatigue conditions, fatigue failure form internal microstructures and inclusions are common. To improve abrasive wear resistance larger carbides are commonly the solution which will have a negative impact on tooling life as these tend to be the root cause of fatigue failures. This has significant impact on cold microforming.

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“…In [9] the effectiveness of such micro structures in strip drawing tests under dry conditions was shown. Samples exhibiting an average roughness of Sa = 200 nm to 400 nm allowed to reduce the coefficient of friction down to 0.21 compared to a polished reference (Sa = 30 nm) with a coefficient of friction of 0.26 [9]. Higher roughness also leads to higher frictional forces.…”

Section: Function-related Applicationmentioning

confidence: 99%

Least-squares Based Parameter Identification for a Function-related Surface Optimisation in Micro Ball-end Milling

Vehmeyer

Piotrowska-Kurczewski

Böhmermann

et al. 2015

Procedia CIRP

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Micro milling is a flexible technique for the production of micro mechanical components like dies and moulds and process control is the key to reach the strong production requirements. Requirements, given by engineers and designers, are addressed mainly to the functional performance of the produced part, therfore topographic features are most decisive. Surface parameters, mainly of statistical origin, have been used for a long time in surface characterisation and process monitoring. Furthermore, it is known that these parameters correlate with the desired functional behaviour, but this knowledge is usually not used for a deterministic process design, uneconomic try and error approaches are still common.Mathematical investigations can use the full process flexibility for an in-process functionalization by selecting optimal conditions and process parameters with respect to a set of relevant surface parameters. In this study, micro ball-end milling is investigated and process parameters in order meet a predefined bearing ratio curve as accurately as possible are identified. Therefore, a mechanistic surface generation model has been developed and is used as a forward model for an iterative optimisation. Static and dynamic process geometry and a micro mechanical material removal operator are the main features of the model. In the first part of the paper the semi-empirical model is calibrated for certain tool and workpiece materials. In the second part optimal feed speed and width of cut are determined. Finally, an experimental validation is presented and the comparison of the predefined, the predicted and the experimental bearing ratio curves shows a good agreement.

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Tribological behavior of micro structured surfaces for micro forming tools

Cited by 74 publications

References 9 publications

Extension of the forming limits of extrusion processes in sheet-bulk metal forming for production of minute functional elements

Extension of the forming limits of extrusion processes in sheet-bulk metal forming for production of minute functional elements

Tool Wear and Life Span Variations in Cold Forming Operations and Their Implications in Microforming

Least-squares Based Parameter Identification for a Function-related Surface Optimisation in Micro Ball-end Milling

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